Highly Sensitive Determination of Uric Acid Based on Zinc Oxide Nanoparticle/Graphene Modified Electrode

Determining the uric acid (UA) concentration in human body fluids (e.g., serum and urine) is required for the diagnosis of several diseases and determination of uric acid is a clinically valuable diagnostic indicator. Uric acid is the primary end product of purine metabolism in the human body. High level of uric acid in the body will lead to several diseases including gout, hyperuricemia and Lesh-Nyhan syndrome [1]. Among several mechanisms of transduction, the electrochemical one has received the largest credit, because of its easiness, low instrumentation cost, capability of miniaturization, and automation. In addition, the use of screen-printed electrodes (SPEs), appeared in the 1990s, largely contributed to this fortune, because of their reliability, reproducibility, mass production, and low cost [2]. Among carbon nanomaterials, graphene has been considered as one of the most promising materials for electrochemical sensing. However, in practical application, the detection limit and selectivity of the graphene are not good, because of their large surface-to-volume ratio leads to lower detection limits [3]. To overcome these obstacles, various materials have been used as matrices for graphene to improve their electrochemical performance. Nanostructured materials including metal oxides have been extensively used for electrochemical sensing applications due to their improved electrocatalytic ability achieved through chemical doping and composite formation [4]. The present study is aimed at the synthesis of the ZnO/GR nanocomposite and its application in the form of the modified screen printed electrode for trace, rapid, and sensitive determination of uric acid through cyclic voltammetric and differential pulse voltammetric techniques. The modified electrode exhibited remarkably anodic peak corresponding to the oxidation of uric acid over the concentration range of 1.0–100.0 μM with detection limit of 0.43 μM (S/N = 3). The fabricated sensor was further 13th Annual Electrochemistry Seminar of Iran Materials and Energy Research Center (MERC), 22- 23 Nov, 2017 71 applied to the detection of uric acid in urine samples with good selectivity and high reproducibility.